Erwin Schrödinger was born in Vienna on August 12, 1887 and was awarded the Nobel Prize in Physics in 1933. He is best known for his work regarding quantum theory, particularly about his thought experiment involving a cat in order to explain the flawed interpretation of quantum superposition.
The Copenhagen Interpretation of quantum mechanics essentially states that an object in a physical system can simultaneously exist in all possible configurations, but observing the system forces the system to collapse and forces the object into just one of those possible states. Schrödinger disagreed with this interpretation.
So what does this have to do with cats? Schrödinger wanted people to imagine that a cat, poison, a geiger counter, radioactive material, and a hammer were inside of a sealed container. The amount of radioactive material was minuscule enough that it only had a 50/50 shot of being detected over the course of an hour. If the geiger counter detected radiation, the hammer would smash the poison, killing the cat. Until someone opened the container and observed the system, it was impossible to predict if the cat’s outcome. Thus, until the system collapsed into one configuration, the cat would exist in some superposition zombie state of being both alive and dead.
Of course, Schrödinger claimed, that was ridiculous. Quantum superposition could not work with large objects such as cats, because it is impossible for an organism to be simultaneously alive and dead. Thus, he reasoned that the Copenhagen Interpretation must be inherently flawed. While many people incorrectly assume Schrödinger supported the premise behind the thought experiment, he really didn’t. His entire point was that it was impossible.
While it is true that modern experiments have revealed that while quantum superposition does work for tiny things like electrons, larger objects must be regarded differently.
This video from Sixty Symbols does an excellent job at explaining the Shrödinger’s Cat Paradox: